1. Field of the Invention
The present invention relates to a driving circuit and a lighting apparatus. More particularly, the present invention relates to a driving circuit used for driving a light emitting diode, and a lighting apparatus using the same.
2. Description of Related Art
Regarding related techniques of a lighting apparatus, a dimmer is generally used for controlling a power supply, so that not only a light-emitting device (for example, a bulb) can be turned on/off, but also a light-emitting effect of the lighting apparatus can be fine-tuned. FIG. 1 is a diagram illustrating a conventional lighting apparatus. Referring to FIG. 1, the lighting apparatus 100 includes a power supply 102, a dimmer 104 and a bulb 106. The power supply 102 provides an input voltage, wherein the input voltage can be an alternating current (AC) power. When a user adjusts a light-emitting effect of the bulb 106 through the dimmer 104, the dimmer 104 can provide a voltage according to a conducting condition thereof, so as to fine-tune the light-emitting effect of the bulb 106. Further, regarding a circuit structure, the light-emitting device (for example, a conventional tungsten bulb) of the conventional lighting apparatus generally has a characteristic as that of a resistor.
With a general technology trend of energy-saving and carbon reduction, a light-emitting diode (LED) lamp gradually becomes a main option for the light-emitting devices. Therefore, based on a cost consideration, in the related art, the bulb 106 is replaced by the LED lamp while the power supply 102 and the dimmer 104 are not changed. Though, regarding the circuit structure, the LED lamp generally has a characteristic as that of a capacitor, so that when the user adjusts the brightness of the LED lamp through the dimmer 104, after the AC power output from the power supply 102 is conducted through the dimmer 104, the voltage provided by the dimmer 104 may result in a flickering phenomenon of the LED lamp.
Therefore, a dimming technique suitable for the LED lamp is provided. An output voltage adjusted by the dimmer 104 is demodulated into an internal corresponding voltage through a LED dimmable application-specific integrated circuit (ASIC), and the corresponding voltage is compared to a triangular wave to obtain a pulse. Then, the pulse drives a power transistor to control a current amount flowing through the LED, so as to achieve a dimming effect of the LED lamp. However, a complexity of peripheral circuits can be increased according to the above technique, and a fabrication cost can be increased due to a high price of a driver IC.